1. Field of the Invention
The present invention relates to a shaking amount detecting apparatus that detects a movement amount on the basis of a detection result of an angular velocity and a detection result of acceleration, an image pickup apparatus including the shaking amount detecting apparatus, and a shaking amount detecting method.
2. Description of the Related Art
In recent years, a camera equipped with an image stabilization function has been generally used. It is possible to photograph a satisfactory image with little conspicuous image blur caused by shaking when holding the camera without paying special attention in hand-held photographing.
However, during long-second photographing in which an exposure time is long, performance of image stabilization is not considered to be sufficient yet and an image blur is sometimes not sufficiently corrected.
In particular, when the long-second photographing is performed in a macro region, sufficient performance is often not obtained with image stabilization functions currently put to practical use.
The image blur in the macro region does not obtain sufficient performance because of a reason explained below.
An image blur of a camera can be classified into an angular motion blur (hereinafter “angle blur”) that occurs when an angle of an optical axis of the camera changes and a translation motion (shifting) blur (hereinafter “translation blur”) that occurs when the camera moves (shifts) in a direction perpendicular to the optical axis.
Most of image stabilization techniques currently put to practical use are techniques for correcting only the former angle blur.
On the other hand, the latter translation blur does not substantially affect image quality when an image magnification is low. However, the influence on quality of a photographed image increases as the image magnification is higher. Sufficient performance cannot be obtained in the macro region with the currently used image stabilization techniques because of this reason (that is, because the image magnification is high in the macro region).
As a technique for solving such a problem, for example, Japanese Patent Application Laid-Open Publication No. 2004-295027 describes a technique including an acceleration sensor that detects acceleration of vibration applied to an interchangeable lens, an angular velocity sensor that detects an angular velocity of the vibration, and a target position converting section that calculates a rotation center of angular vibration on the basis of detection results of the acceleration and the angular velocity by the acceleration sensor and the angular velocity sensor and calculates a target position of an image stabilization lens. The image stabilization apparatus drives the image stabilization lens on the basis of a calculation result obtained by the target position converting section and corrects a blur of an image.
Japanese Patent Application Laid-Open Publication No. 2010-243824 describes an image blur correction apparatus including a photographing optical system that photographs an object, angular velocity detecting means for detecting and outputting an angular velocity applied to the image blur correction apparatus, acceleration detecting means for detecting and outputting acceleration applied to the image blur correction apparatus, rotation angular velocity calculating means for calculating a rotation angular velocity component centering on a main point of the photographing optical system on the basis of the output of the angular velocity detecting means, revolution angular velocity calculating means for calculating a revolution angular velocity component about an object on the basis of the output of the acceleration detecting means and a calculation result of the rotation angular velocity calculating means, and control means for performing image blur correction control on the basis of a difference value between the rotation angular velocity component and the revolution angular velocity component. According to the technique, irrespective of in what kind of state angular vibration and parallel vibration are mixed, it is possible to perform correct image blur correction without a failure of control and computation complexity is reduced.
In the technique described in Japanese Patent Application Laid-Open Publication No. 2004-295027, a blur amount of an image surface is calculated on the basis of a translation blur due to rotational motions in a yaw direction and a pitch direction. However, a translation blur due to a rotational motion in a roll direction is not taken into account. Since the translation blur is also caused by the rotational motion in the roll direction, it is preferable to take this point into account to detect a blur amount accurately.
This point is explained with reference to FIG. 1 and FIG. 2A to FIG. 2C according to this application.
First, as shown in FIG. 1, when an optical axis direction of an optical system 2 is represented as Z direction, a horizontal direction of a camera 1 in a standard posture is represented as X direction, and a vertical direction of the camera 1 in the standard posture is represented as Y direction, a rotational motion about a Z axis, which is a first axis, is roll, a rotational motion about a Y axis, which is a second axis, is yaw, and a rotational motion about an X axis, which is a third axis, is pitch.
As shown in FIG. 2A, when the rotational motion in the yaw direction occurs in the camera 1, a movement amount in the X direction is generated. As shown in FIG. 2B, when a rotational motion in the pitch direction occurs in the camera 1, a movement amount in the Y direction is generated.
However, a translation blur that occurs in the camera 1 is not caused only by these rotational motions. It is seen that, as shown in FIG. 2C, when a rotational motion in the roll direction occurs in the camera 1, a movement amount including a movement amount component in the X direction and a movement amount component in the Y direction is generated.
In the technique described in Japanese Patent Application Laid-Open Publication No. 2010-243824, a complicated calculation is performed taking into account a focus vibration, a centripetal force of revolution, acceleration of the revolution, a Coriolis force, a centripetal force of rotation, acceleration of the rotation, a gravitational acceleration component, and the like using, for example, a polar coordinate system.